There are a number of factors that contribute to hazardous conditions for boaters that travel in close proximity to a dam. These include multiple sources of water that can be discharged from a dam, the release of large volumes of water that result in the development of strong currents, rapidly changing conditions, the presence of highly turbulent water, and the presence of cold water that could lead to hypothermia and shock. Any one of these factors can be problematic to boaters, and when experienced in combination can lead to catastrophic results.
· Conditions downstream of dams can be extremely hazardous to boaters due to large amounts of water that can be discharged through a dam. Because a significant increase in the flow of water can occur within a matter of only seconds, resulting turbulent waters and swift currents can capsize boats and render small boats uncontrollable.
· Turbine generation discharges directly below a dam can be extremely dangerous to boaters creating conditions that can capsize or overturn boats. When turbine generation begins, the release of water into the river below the dam can create turbulence and possible undertows. Boils or upwellings caused by the release of water through the turbine can flip boats. Certain hydropower operations can lead to the sudden release of a large volume of air into the river downstream resulting in reduced buoyancy for boats in these areas.
· Spillway releases from a dam can create undertows, eddies and whirlpools resulting in very dangerous conditions for boaters. Boats can be drawn into the spillway release and flooded. While large spillway releases present obvious dangers, even a small release can be deadly. The power of water should never be underestimated.
· Navigation locks may fill or empty at irregular intervals and the volumes of water involved are considerable. Lock discharge locations may not be easily discerned and sudden discharges from lock chamber emptying can create turbulent boils and powerful currents capable of swamping a small boat. In general, lock chambers should be given a wide berth in order to avoid these dangers.
· Sluice releases from dams cause extremely turbulent waters below dams. Violent, irregular wave actions are common with sluice releases and can swamp or overturn boats.
· On the upstream side of dams, there is a strong undertow created by the flow of water through the gated section of the dam. Boats approaching too closely from the upstream side are in danger of being lodged against the dam or capsized by the undertow.